The fate of patulin in apple juice processing: A review

Effect of antifungal proteins (AFPs) on the viability of heat-resistant fungi (HRFs) and the preservation of fruit juices

The control of heat-resistant fungi (HRFs), which cause spoilage of heat-treated fruit products, is considered a challenge for the fruit juice and beverage industry and requires new strategies for the development of antifungal compounds. In this study, four antifungal proteins (AFPs) from Penicillium digitatum (PdAfpB) and Penicillium expansum (PeAfpA, PeAfpB and PeAfpC), were evaluated against conidia from a representative collection of HRFs. A total of 19 strains from 16 different species belonging to the genera Aspergillus, Hamigera, Paecilomyces, Rasamsonia, Sarocladium, Talaromyces and Thermoascus were included in the study. PeAfpA and PdAfpB exhibited potent antifungal activity in synthetic media, completely inhibiting the growth of most of the fungi evaluated in the range of 0.5-32 μg/mL. The efficacy of the four AFPs was also tested in fruit juices against ascospores of five HRFs relevant to the food industry, including P. fulvus, P. niveus, P. variotii, A. fischeri and T. flavus. PdAfpB was the most effective protein in fruit juices, since it completely inhibited the growth of the five species tested in at least one of the fruit juices evaluated. This is the first study to demonstrate the activity of AFPs against fungal ascospores. Finally, a challenge test study showed that PdAfpB, at a concentration of 32 μg/mL, protected apple fruit juice artificially inoculated with ascospores of P. variotii for 17 days, highlighting the potential of the protein as a preservative in the fruit juice industry.

Effects of apples (Malus domestica) and their derivatives on metabolic conditions related to inflammation and oxidative stress and an overview of by-products use in food processing

Apple (Malus domestica) is the third most produced fruit worldwide. It is a well-known source of bioactive compounds mainly represented by hydroxycinnamic acids, flavan-3-ols, dihydrochalcones, dehydroascorbic acid, carotenoids, chlorogenic acid, epicatechin, and phloridzin. Due to the lack of a recent evaluation of the clinical trials associated with apple consumption, this review investigated the effects of this fruit on metabolic conditions related to inflammation and oxidative stress and reviewed the applications of apple waste on food products. Thirty-three studies showed that apples or its derivatives exhibit anti-inflammatory and antioxidant actions, improve blood pressure, body fat, insulin resistance, dyslipidemia, and reduce cardiovascular risks. Apples have a great economic impact due to its several applications in the food industry and as a food supplement since it has impressive nutritional value. Dietary fiber from the fruit pomace can be used as a substitute for fat in food products or as an improver of fiber content in meat products. It can also be used in bakery and confectionary products or be fermented to produce alcohol. Pomace phytocompounds can also be isolated and applied as antioxidants in food products. The potential for the use of apples and by-products in the food industry can reduce environmental damage.

Determination of Patulin in Apple Juice and Apple-Derived Products Using a Robotic Sample Preparation System and LC-APCI-MS/MS

Patulin, a toxic mycotoxin, can contaminate apple-derived products. The FDA has established an action level of 50 ppb (ng/g) for patulin in apple juice and apple juice products. To effectively monitor this mycotoxin, there is a need for adequate analytical methods that can reliably and efficiently determine patulin levels. In this work, we developed an automated sample preparation workflow followed by liquid chromatography-atmospheric pressure chemical ionization tandem mass spectrometry (LC-APCI-MS/MS) detection to identify and quantify patulin in a single method, further expanding testing capabilities for monitoring patulin in foods compared to traditional optical methods. Using a robotic sample preparation system, apple juice, apple cider, apple puree, apple-based baby food, applesauce, fruit rolls, and fruit jam were fortified with 13C-patulin and extracted using dichloromethane (DCM) without human intervention, followed by an LC-APCI-MS/MS analysis in negative ionization mode. The method achieved a limit of quantification of 4.0 ng/g and linearity ranging from 2 to 1000 ng/mL (r2 > 0.99). Quantitation was performed with isotope dilution using 13C-patulin as an internal standard and solvent calibration standards. Average recoveries (relative standard deviations, RSD%) in seven spike matrices were 95% (9%) at 10 ng/g, 110% (5%) at 50 ng/g, 101% (7%) at 200 ng/g, and 104% (4%) at 1000 ng/g (n = 28). The ranges of within-matrix and between-matrix variability (RSD) were 3-8% and 4-9%, respectively. In incurred samples, the identity of patulin was further confirmed with a comparison of the information-dependent acquisition-enhanced product ion (IDA-EPI) MS/MS spectra to a reference standard. The metrological traceability of the patulin measurements in an incurred apple cider (21.1 ± 8.0 µg/g) and apple juice concentrate (56.6 ± 15.6 µg/g) was established using a certified reference material and calibration data to demonstrate data confidence intervals (k = 2, 95% confidence interval).

New insights into searching patulin degrading enzymes in Saccharomyces cerevisiae through proteomic and molecular docking analysis

Global warming has increased the contamination of mycotoxins. Patulin (PAT) is a harmful contaminant that poses a serious threat to food safety and human health. Saccharomyces cerevisiae biodegrades PAT by its enzymes during fermentation, which is a safe and efficient method of detoxification. However, the key degradation enzymes remain unclear. In this study, the proteomic differences of Saccharomyces cerevisiae under PAT stress were investigated. The results showed that the proteins involved in redox reactions and defense mechanisms were significantly up-regulated to resist PAT stress. Subsequently, molecular docking was used to virtual screen for degrading enzymes. Among 18 proteins, YKL069W showed the highest binding affinity to PAT and was then expressed in Escherichia coli, where the purified YKL069W completely degraded 10 μg/mL PAT at 48 h. YKL069W was demonstrated to be able to degrade PAT into E-ascladiol. Molecular dynamics simulations confirmed that YKL069W was stable in catalyzing PAT degradation with a binding free energy of - 7.5 kcal/mol. Furthermore, it was hypothesized that CYS125 and CYS101 were the key amino acid residues for degradation. This study offers new insights for the rapid screening and development of PAT degrading enzymes and provides a theoretical basis for the detoxification of mycotoxins.

Application of Immobilized Enzymes in Juice Clarification

Immobilized enzymes are currently being rapidly developed and are widely used in juice clarification. Immobilized enzymes have many advantages, and they show great advantages in juice clarification. The commonly used methods for immobilizing enzymes include adsorption, entrapment, covalent bonding, and cross-linking. Different immobilization methods are adopted for different enzymes to accommodate their different characteristics. This article systematically reviews the methods of enzyme immobilization and the use of immobilized supports in juice clarification. In addition, the mechanisms and effects of clarification with immobilized pectinase, immobilized laccase, and immobilized xylanase in fruit juice are elaborated upon. Furthermore, suggestions and prospects are provided for future studies in this area.

Analysis of Patulin in Apple Products Marketed in Belgium: Intra-Laboratory Validation Study and Occurrence

Apple and apple derivatives (e.g., juices, puree) are the most important foodstuffs contaminated with patulin (PAT) in the human diet. To routinely monitor these foodstuffs and ensure that the PAT levels are below the maximum permitted levels, a method using liquid chromatography combined with tandem mass spectrometry (LC-MS/MS) has been developed. Afterwards, the method was successfully validated, reaching quantification limits of 1.2 μg/L for apple juice and cider, and 2.1 μg/kg for puree. Recovery experiments were performed with samples fortified with PAT in the range of 25-75 μg/L for juice/cider and 25-75 μg/kg for puree. The results show overall average recovery rates of 85% (RSD_r = 13.1%) and 86% (RSD_r = 2.6%) with maximum extended uncertainty (U_max, k = 2) of 34 and 35% for apple juice/cider and puree, respectively. Next, the validated method was applied to 103 juices, 42 purees and 10 ciders purchased on the Belgian market in 2021. PAT was not found in the cider samples, but it was present in 54.4% of the tested apple juices (up to 191.1 μg/L) and 7.1% of the puree samples (up to 35.9 μg/kg). When comparing the results to the maximum levels set by Regulation EC n° 1881/2006 (i.e., 50 μg/L for juices and 25 μg/kg for puree for adults, and 10 μg/kg for infants and young children), exceedances were observed in five apple juices and one puree sample, for infants and young children. Using these data, a potential risk assessment for consumers can be suggested, and it is found that the quality of apple juices and purees sold in Belgium needs further regular surveillance.

Patulin Alters Insulin Signaling and Metabolic Flexibility in HepG2 and HEK293 Cells

Non-communicable diseases (NCDs) have risen rapidly worldwide, sparking interest in causative agents and pathways. Patulin (PAT), a xenobiotic found in fruit products contaminated by molds, is postulated to be diabetogenic in animals, but little is known about these effects in humans. This study examined the effects of PAT on the insulin signaling pathway and the pyruvate dehydrogenase complex (PDH). HEK293 and HepG2 cells were exposed to normal (5 mM) or high (25 mM) glucose levels, insulin (1.7 nM) and PAT (0.2 μM; 2.0 μM) for 24 h. The qPCR determined gene expression of key enzymes involved in carbohydrate metabolism while Western blotting assessed the effects of PAT on the insulin signaling pathway and Pyruvate Dehydrogenase (PDH) axis. Under hyperglycemic conditions, PAT stimulated glucose production pathways, caused defects in the insulin signaling pathway and impaired PDH activity. These trends under hyperglycemic conditions remained consistent in the presence of insulin. These findings are of importance, given that PAT is ingested with fruit and fruit products. Results suggest PAT exposure may be an initiating event in insulin resistance, alluding to an etiological role in the pathogenesis of type 2 diabetes and disorders of metabolism. This highlights the importance of both diet and food quality in addressing the causes of NCDs.

Implementation of the HACCP System for Apple Juice Concentrate Based on Patulin Prevention and Control

Patulin (PAT) is a toxic secondary metabolite produced by Aspergillus sp. and Penicillium sp., which acts as a contaminant of most apples and their products. The internationally recognized HACCP system is selected as the theoretical basis to more effectively reduce the PAT in apple juice concentrate (AJC). Through field investigation of apple juice concentrate (AJC) production enterprises, we collected 117 samples from 13 steps of AJC production, including whole apple, apple pulp, and apple juice. PAT contents were analyzed via high-performance liquid chromatography (HPLC) and compared with samples from the different production processes. The result demonstrated that the PAT content was significantly (p < 0.05) influenced by five processes, receipt of raw apples, sorting of raw apples, adsorption step, pasteurization, and aseptic filling. These processes were determined as the CCPs. Monitoring systems for maintaining CCPs within acceptable limits were established, and corrective actions were proposed in case a CCP was surpassed. Based on the above-identified CCPs, critical limits, and control methods (corrective actions), a HACCP plan related to the production process of AJC was established. This study provided important guidance for juice manufacturers wishing to effectively control the PAT content in their products.

Possible Reaction Mechanisms Involved in Degradation of Patulin by Heat-Assisted Cysteine under Highly Acidic Conditions

Patulin (PAT) is one of mycotoxins that usually contaminates apple juice, and it is not easily detoxified by cysteine (CYS) at room temperature due to the highly acidic conditions based on the Michael addition reaction. However, it could be effectively degraded by a heating treatment at 120 °C for 30 min in the presence of cysteine. In our study, a total of eight degradation products (DP A–H) were characterized and identified via liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) in a negative ion mode, and their structures and formulas were proposed based on their accurate mass data. The fragmentation patterns of PAT and its degradation products were obtained from the MS/MS analysis. Meanwhile, the possible reaction mechanisms involved in the degradation of PAT were established and explained for the first time. According to the relation between the structure and toxicity of PAT, it could be deduced that the toxic effects of PAT degradation products were potentially much less than those of PAT-self.

Development and validation of a label-free colorimetric aptasensor based on the HCR and hemin/G-quadruplex DNAzyme for the determination of patulin in fruits and fruit-based products from Xinjiang (China)

In this study, a simple, novel and practical label-free colorimetric aptasensor was successfully prepared for the ultrasensitive detection of patulin, based on the hybridization chain reaction (HCR) and hemin/G-quadruplex DNAzyme-signal amplification strategy. In this aptasensor, a detection probe was designed consisting of the aptamer sequence for the patulin and an initiator sequence to trigger the HCR. Two hairpin structures (H1 and H2) that included the G-quadruplex sequences in inactive configuration were used as functional elements. The presence of patulin triggered the opening of the hairpin structure and the beginning of the HCR. After the addition of hemin, G-rich DNA self-assembled into the peroxidase-mimicking hemin/G-quadruplex DNAzymes, which catalyzed a colorimetric reaction. Under optimized conditions, patulin was measured within a linear range of 0.1-200 ng mL^-1, and the detection limit was 0.060 ng mL^-1. The recovery rates ranged from 91.4 to 105% for fruits and fruit-based products. Subsequently, a total of 311 samples comprising fruits, fruit-based products and dried fruits were collected from supermarkets, production bases and farmers' markets in Xinjiang, and analyzed for patulin using the proposed aptasensor. Patulin was detected in 16 samples (5.14%) at concentrations ranging from 1.23 to 16.4 μg kg^-1. None of the samples exceeded the maximal level set by the EU commission (50 μg kg^-1). The positivity in fresh fruits (7.69%) was significantly higher than that of fruit-based products (4.00%) and dried fruits (1.25%). In summary, the proposed aptasensor can quickly detect patulin in food samples, thus providing a warning for mycotoxin contamination.

Occurrence and Characterization of Penicillium Species Isolated from Post-Harvest Apples in Lebanon

The apple is one of the most important fruit tree crops in the Mediterranean region. Lebanon, in particular, is among the top apple producer countries in the Middle East; however, recently, several types of damage, particularly rot symptoms, have been detected on fruits in cold storage. This study aims to identify the causal agents of apple decay in Lebanese post-harvest facilities and characterize a set of 39 representative strains of the toxigenic fungus Penicillium. The results demonstrated that blue mould was the most frequent fungal disease associated with apples showing symptoms of decay after 3–4 months of storage at 0 °C, with an average frequency of 76.5% and 80.6% on cv. Red and cv. Golden Delicious apples, respectively. The morphological identification and phylogenetic analysis of benA gene showed that most Penicillium strains (87.2%) belong to P. expansum species whereas the remaining strains (12.8%) belong to P. solitum. Furthermore, 67.7% of P. expansum strains produced patulin when grown on apple puree for 14 days at 25 °C with values ranging from 10.7 mg kg⁻¹ to 125.9 mg kg⁻¹, whereas all P. solitum did not produce the mycotoxin. This study highlights the presence of Penicillium spp. and their related mycotoxin risk during apple storage and calls for the implementation of proper measures to decrease the risk of mycotoxin contamination of apple fruit products.

Eco-friendly control of licorice aqueous extract to increase quality and resistance to postharvest decay in apple and tangerine fruits

BACKGROUND

Postharvest diseases in fruits and vegetables are one of the major problems in storing them as a fresh agri-product. This study aimed to investigate the antifungal activity of licorice (Glycyrrhiza glabra) aqueous extract against the Penicillium expansum and the Penicillium digitatum in apple and tangerine fruits as well as their postharvest decay during storage time.

METHODS

The minimum inhibitory concentration (MIC) of the molds, and the decay inhibition percentage (%DI) with the P.expansum for apple and P.digitatum for tangerine after treatment with licorice aqueous extract were measured. Additionally, the lesion diameter, titratable acidity (TA), total soluble solids (TSS), pH, and organoleptic properties were determined.

RESULTS

The growth of molds was almost inhibited at the concentration of 62.5 mg/mL. The ability of licorice aqueous extract to significantly control and reduce the growth of P. expansum in apple by 60 and 20 % after 7 days and 21 days of storage time was proved, respectively. Furthermore, significant differences in pH and TSS (p < 0.05) were observed in apples. Also, the growth of P. digitatum in the tangerine reduced by 33.3 % after 7 days, while there was no significant difference between the control and treatment groups in pH and TSS for apples, and similarly, there was no significant difference in TA for tangerine samples.

CONCLUSIONS

Therefore, the licorice aqueous extract treatment could postpone the blue mold decay in apple fruits and green mold decay in tangerine without any significant effect on fruit quality characteristics. It can be considered as a new eco-friendly control in fruit preservation, while it did not result in any significant adverse effect on  the quality.

Critical Assessment of Mycotoxins in Beverages and Their Control Measures

Mycotoxins are secondary metabolites of filamentous fungi that contaminate food products such as fruits, vegetables, cereals, beverages, and other agricultural commodities. Their occurrence in the food chain, especially in beverages, can pose a serious risk to human health, due to their toxicity, even at low concentrations. Mycotoxins, such as aflatoxins (AFs), ochratoxin A (OTA), patulin (PAT), fumonisins (FBs), trichothecenes (TCs), zearalenone (ZEN), and the alternaria toxins including alternariol, altenuene, and alternariol methyl ether have largely been identified in fruits and their derived products, such as beverages and drinks. The presence of mycotoxins in beverages is of high concern in some cases due to their levels being higher than the limits set by regulations. This review aims to summarize the toxicity of the major mycotoxins that occur in beverages, the methods available for their detection and quantification, and the strategies for their control. In addition, some novel techniques for controlling mycotoxins in the postharvest stage are highlighted.

Patulin in food: A mycotoxin concern for human health and its management strategies

The mycotoxin patulin is primarily produced as a secondary metabolite by numerous fungal species and predominantly by Aspergillus, Byssochlamys, and Penicillium species. It is generally associated with fungal infected food materials. Penicillium expansum is considered the only fungal species liable for patulin contamination in pome fruits, especially in apples and apple-based products. This toxin in food poses serious health concerns and economic threat, which has aroused the need to adopt effective detection and mitigation strategies. Understanding its origin sources and biosynthetic mechanism stands essential for efficiently designing a management strategy against this fungal contamination. This review aims to present an updated outline of the sources of patulin occurrence in different foods and their biosynthetic mechanisms. It further provides information regarding the detrimental effects of patulin on human and agriculture as well as its effective detection, management, and control strategies.

Fungal natural products galaxy: Biochemistry and molecular genetics toward blockbuster drugs discovery

Secondary metabolites synthesized by fungi have become a precious source of inspiration for the design of novel drugs. Indeed, fungi are prolific producers of fascinating, diverse, structurally complex, and low-molecular-mass natural products with high therapeutic leads, such as novel antimicrobial compounds, anticancer compounds, immunosuppressive agents, among others. Given that these microorganisms possess the extraordinary capacity to secrete diverse chemical scaffolds, they have been highly exploited by the giant pharma companies to generate small molecules. This has been made possible because the isolation of metabolites from fungal natural sources is feasible and surpasses the organic synthesis of compounds, which otherwise remains a significant bottleneck in the drug discovery process. Here in this comprehensive review, we have discussed recent studies on different fungi (pathogenic, non-pathogenic, commensal, and endophytic/symbiotic) from different habitats (terrestrial and marines), the specialized metabolites they biosynthesize, and the drugs derived from these specialized metabolites. Moreover, we have unveiled the logic behind the biosynthesis of vital chemical scaffolds, such as NRPS, PKS, PKS-NRPS hybrid, RiPPS, terpenoids, indole alkaloids, and their genetic mechanisms. Besides, we have provided a glimpse of the concept behind mycotoxins, virulence factor, and host immune response based on fungal infections.

Leuconostoc mesenteroides subsp. mesenteroides LB7 isolated from apple surface inhibits P. expansum in vitro and reduces patulin in fruit juices

This research aimed to isolate lactic acid bacteria (LAB) from apple surface and to reveal their potential to inhibit the growth of Penicillium expansum. Besides, their ability to detoxify fruit juices contaminated with mycotoxin patulin, produced by this fungi, was also studied. The isolation was performed on a typical MRS medium under ambient conditions. The molecular identification of the strains was done by sequencing the 16S rRNA genes. Antifungal activities of the isolated strains have been evaluated using dual agar plate assay protocol. A total of 11 LAB isolates was obtained from apples. These isolates showed phenotypic traits consistent with the genera of LAB. They have been identified as Leuconostoc mesenteroides subsp. mesenteroides and Weissella paramesenteroides. Among them, the strain LB7 showed exciting inhibitory activities in vitro against P. expansum. LB7 also successfully detoxified homemade and commercial fruit juices contaminated with patulin. Further research will bring the application prospects of these LABs in food biocontrol and biopreservation strategies.

Using extended Bigelow meta-regressions for modelling the effects of temperature, pH, °Brix on the inactivation of heat resistant moulds

The management of Heat Resistant Moulds (HRMs) is considered a great challenge for the juice fruit industry. Neosartorya, Byssochlamys and Talaromyces are three out of the main genera isolated from fruit juices that show great resistance to heat treatments. Several inactivation parameters can be found in the literature, however all of them were carried out in specific food matrices and using diverse inactivation methods. Thus, this meta-analysis study synthesizes the thermal resistance parameters of the three HRMs by adjusting extended Bigelow-based meta-regression models to data on inactivation experiments conducted in different liquid media. The meta-analytical data, extracted from publications between 1969 and 2017, was composed of decimal reduction time (D), inactivation method, temperature of inactivation, pH, °Brix, age of spores, and type of medium (model, juice, concentrates). Pooled D* values (D at 90 °C, pH 3.5 and 12° Brix) were estimated for B. fulva (1.95 min; 95% CI: 1.21-3.11 min), Talaromyces (4.03 min; 95% CI: 3.43-4.74 min), Neosartorya (0.5.35 min; 95% CI: 4.10-7.08 min), and B. nivea (10.32 min; 95% CI: 5.81-18.4 min). It was found that increasing the soluble solids in concentrates tends to cause a lower decrease in the heat resistance of Neosartorya and Talaromyces than increasing the soluble solids in model liquid or juices (p = 0.001; 0.012). In general, the screw-capped tubes and three neck round inactivation methods render higher D* values (p < 0.05) than the thermal death tubes, the polyethylene bag and the capillary methods. Spores of Talaromyces (overall z_pH = 7.56; 95% CI: 5.13-13.5) and Neosartorya (overall z_pH = 7.07; 95% CI: 5.04-10.8) appear to be more thermal sensitive to a decrease in medium pH than spores of Byssochlamys (overall z_pH = 4.34; 95% CI: 3.20-6.73). The meta-regression models presented in this study can be valuable for estimating pooled inactivation kinetic parameters to be used by the fruit juice industry in the management of thermal processes and in the determination of shelf-life.

Patulin suppresses α1-adrenergic receptor expression in HEK293 cells

Patulin (PAT) is a common mycotoxin contaminant of apple products linked to impaired metabolic and kidney function. Adenosine monophosphate activated protein kinase (AMPK), abundantly expressed in the kidney, intercedes metabolic changes and renal injury. The alpha-1-adrenergic receptors (α₁-AR) facilitate Epinephrine (Epi)-mediated AMPK activation, linking metabolism and kidney function. Preliminary molecular docking experiments examined potential interactions and AMPK-gamma subunit 3 (PRKAG3). The effect of PAT exposure (0.2-2.5 µM; 24 h) on the AMPK pathway and α₁-AR was then investigated in HEK293 human kidney cells. AMPK agonist Epi determined direct effects on the α₁-AR, metformin was used as an activator for AMPK, while buthionine sulphoximine (BSO) and N-acetyl cysteine (NAC) assessed GSH inhibition and supplementation respectively. ADRA1A and ADRA1D expression was determined by qPCR. α₁-AR, ERK1/2/MAPK and PI3K/Akt protein expression was assessed using western blotting. PAT (1 µM) decreased α₁-AR protein and mRNA and altered downstream signalling. This was consistent in cells stimulated with Epi and metformin. BSO potentiated the observed effect on α₁-AR while NAC ameliorated these effects. Molecular docking studies performed on Human ADRA1A and PRKAG3 indicated direct interactions with PAT. This study is the first to show PAT modulates the AMPK pathway and α₁-AR, supporting a mechanism of kidney injury.

Recent trends in detecting, controlling, and detoxifying of patulin mycotoxin using biotechnology methods

Patulin (PAT) is a mycotoxin that can contaminate many foods and especially fruits and fruit-based products. Therefore, accurate and effective testing is necessary to enable producers to comply with regulations and promote food safety. Traditional approaches involving the use of chemical compounds or physical treatments in food have provided practical methods that have been used to date. However, growing concerns about environmental and health problems associated with these approaches call for new alternatives. In contrast, recent advances in biotechnology have revolutionized the understanding of living organisms and brought more effective biological tools. This review, therefore, focuses on the study of biotechnology approaches for the detection, control, and mitigation of PAT in food. Future aspects of biotechnology development to overcome the food safety problem posed by PAT were also examined. We find that biotechnology advances offer novel, more effective, and environmental friendly approaches for the control and elimination of PAT in food compared to traditional methods. Biosensors represent the future of PAT detection and use biological tools such as aptamer, enzyme, and antibody. PAT prevention strategies include microbial biocontrol, the use of antifungal biomolecules, and the use of microorganisms in combination with antifungal molecules. PAT detoxification aims at the breakdown and removal of PAT in food by using enzymes, microorganisms, and various adsorbent biopolymers. Finally, biotechnology advances will be dependent on the understanding of fundamental biology of living organisms regarding PAT synthesis and resistance mechanisms.

Effects of ascorbic acid on patulin in aqueous solution and in cloudy apple juice

Degradation of the mycotoxin patulin (PAT) and the generation of (less toxic) breakdown products, such as (E/Z)-ascladiol (ASC-E/Z) and desoxypatulinic acid (D-PAT), can occur due to chemical, physical and biological treatments. Our study focused on the chemical degradation of PAT in the presence of ascorbic acid (AA) both for pure PAT standard in acidified aqueous solution and for PAT-contaminated cloudy apple juice (CAJ) (obtained via addition of apple mash produced from apples inoculated with Penicillium expansum). Within this framework, different concentrations of AA were evaluated, as well as the presence/absence of oxygen and different storage temperatures. In order to do so, an in-house methodology allowing a good separation of PAT from its reaction and breakdown products was optimized first. The highest PAT reduction (60%) in CAJ with an initial PAT concentration of 100 μg/kg and 0.25% (w/v) AA was achieved after 6 days of incubation at 22 °C in the presence of oxygen. It was also found that the treatment by AA resulted in the generation of degradation products less toxic than PAT (such as (E/Z)-ASC). In conclusion, AA used to improve numerous product quality aspects (e.g. colour (less browning), nutritional value, etc.) and considered as a safe food additive (Food and Drug Administration (FDA) (1999)) has an effect on PAT degradation. It was shown that such degradation generated less toxic compounds in the presence of oxygen. In view of consumers' safety, fortification of apple juice (and possibly apple-based products) with AA could be helpful within an integrated system to ensure products with low levels of patulin. The optimum conditions for such an approach within a legal and practical point of view need to be further explored.

Occurrence of patulin and 5-hydroxymethylfurfural in apple sour, which is a traditional product of Kastamonu, Turkey

Apple sour is a traditional product of Kastamonu, Turkey. It is consumed by spreading on bread or drinking after diluting with water. The aim of this study was to determine patulin (PAT) and 5-hydroxymethylfurfural (HMF) in apple sour. This study is the first to evaluate the occurrence of PAT and HMF in apple sour. The samples were extracted with ethyl acetate using liquid-liquid extraction technique. PAT and HMF were determined by HPLC with UV detection. PAT was detected in all samples, and the PAT level in 94.9% of samples was found to be equal or greater than the legal limit for juice concentrates. The mean value for PAT was found to be 284 ± 307 μg kg^-1. PAT levels in 13 of 39 samples were in the range of 100 ≤ x < 200 μg kg^-1, two samples were in the range of 0 ≤ x < 50 μg kg -1 and two samples were in the range of 1000 ≤ x < 1500 μg kg¹. HMF levels of all samples were above the legal limit for solid molasses. The mean value for HMF was found to be 16215 ± 13317 mg kg^-1. HMF levels of 10 of 39 samples were determined to be in the range of 10000 ≤ x < 20000 mg kg^-1, eight samples were in the range of 20000 ≤ x < 30000 mg kg^-1 and only three samples were in the range of 100 ≤ x < 1000 mg kg^-1. There was a significant and inverse relationship between HMF and pH of the samples. These results indicate that consumption of apple sour is a considerable risk in terms of HMF and PAT toxicity.

The characteristics, occurrence, and toxicological effects of patulin

Mycotoxins are the secondary metabolites secreted by different types of fungi to which humans can get exposed mainly via ingestion. Patulin (C₇H₆O₄) is a polyketide lactone produced by various fungal specifies, including Penicillium expansum as the main producer. P. expansum can infect different fruits and vegetables yet it has preference to apples in which they cause blue rot. Therefore, apples and apple-based food products are the main source of Patulin exposure for humans. Patulin was first identified in 1943 under the name of tercinin as a possible antimicrobial agent. Although it is categorized as a non-carcinogen, Patulin has been linked, in the last decades, to neurological, gastrointestinal, and immunological adverse effects, mainly causing liver and kidney damages. In this review, the characteristics of and possible human exposure pathways to Patulin are discussed. Various surveillance and toxicity studies on the levels of Patulin in various food products and effects of Patulin on cells and animal models have been documented as well. Importance of epidemiological studies and a summary of the possible toxicity mechanisms are highlighted with a case study. The commonly used control methods as described in the literature are also discussed to guide future researchers to focus on mitigating mycotoxins contamination in the food industry.

Patulin removal from synbiotic apple juice using Lactobacillus plantarum ATCC 8014

AIMS

The aim of this study was to evaluate the elimination of patulin (PAT) by Lactobacillus plantarum ATCC 8014 from artificially contaminated apple juice and its dependence on prebiotic, citric acid and ascorbic acid content.

METHODS AND RESULTS

A central composite design was used for studying each of the three factors at five levels to find the optimum concentrations. The results showed that inserting 2·3% (w/v) fructooligosaccharide, 213 mg l^-1 ascorbic acid and 1·4 g l^-1 citric acid to apple juice with inoculating 3·6 × 10¹¹ CFU per ml, L. plantarum improved the efficiency of PAT removal to 95·91% during 6 weeks cold storage. SDS-PAGE of cell surface proteins of probiotics revealed that surface layer proteins have an important role in PAT removal from apple juice. No significant difference was observed in the flavour and colour of the optimized synbiotic apple juice and in the control sample until 3 weeks of cold storage.

CONCLUSION

Lactobacillus plantarum ATCC 8014 is capable of PAT removal from artificially contaminated synbiotic apple juice.

SIGNIFICANCE AND IMPACT OF THE STUDY

Synbiotic apple juice artificially contaminated with PAT will be safe for consumers after the first day of probiotic inoculation; and surface layer proteins of probiotic cells are responsible for PAT removal.

How sulphur dioxide and storage temperature contribute to patulin degradation in homemade apple juice

Mycotoxin patulin is one of the quality indicators for apple juice. Like other mycotoxins, it raises consumer health concerns. The issue of low quality is particularly relevant for apples provided by small producers, whose quality control may not be standardised. As sulphur dioxide (SO2) is common in fruit preservation against fungi, the aim of this study was to determine how efficient it is in degrading patulin in apple juices stored in real-life conditions. This included refrigerated (4 °C) and non-refrigerated warehouses/environments (30 °C) over 8, 10, 12, and 20 weeks of storage. Apple juice was diluted to 0.010 μg g-1, 0.050 μg g-1, and 0.100 μg g-1 of patulin. SO2 was added to each sample in the amounts of 250 μg mL-1 and 50 μg mL-1. Untreated juice samples for each patulin concentration served as controls under the same experimental conditions. Patulin content was determined with high performance liquid chromatography. The best degradation was observed with 250 μg mL-1 of SO2 at 30 °C regardless of the patulin baseline concentration. Although treatment with SO2 and refrigeration did not fully remove patulin, it was highly efficient over twelve weeks of storage. Our results suggest that patulin levels can be reduced between 33 and 100 % at 30 °C and up to 100 % at 4 °C.

Effect of Compound Probiotics and Mycotoxin Degradation Enzymes on Alleviating Cytotoxicity of Swine Jejunal Epithelial Cells Induced by Aflatoxin B₁ and Zearalenone

Zearalenone (ZEA) and aflatoxin B₁ (AFB₁) are two main kinds of mycotoxins widely existing in grain and animal feed that cause a lot of economic loss and health problems for animals and humans. In order to alleviate the cytotoxic effects of AFB₁ and ZEA on swine jejunal epithelial cells (IPEC-J2), the combination of a cell-free supernatant of compound probiotics (CFSCP) with mycotoxin degradation enzymes (MDEs) from Aspergillus oryzae was tested. The results demonstrated that coexistence of AFB₁ and ZEA had synergetic toxic effects on cell viability. The cell viability was decreased with mycotoxin concentrations increasing, but increased with incubation time extension. The necrotic cell rates were increased when 40 µg/L AFB₁ and/or 500 µg/L ZEA were added, but the addition of CFSCP + MDE suppressed the necrotic effects of AFB₁ + ZEA. The viable cell rates were decreased when AFB₁ and/or ZEA were added: However, the addition of CFSCP + MDE recovered them. The relative mRNA abundances of Bcl-2, occludin, and ZO-1 genes were significantly upregulated, while Bax, caspase-3, GLUT2, ASCT2, PepT1, and IL6 genes were significantly downregulated by CFSCP + MDE addition, compared to the groups containing 40 µg/L AFB₁ and 500 µg/L ZEA. This research provided an effective strategy in alleviating mycotoxin cytotoxicity and keeping normal intestinal cell structure and animal health.

Isotopic Labeling Studies Reveal the Patulin Detoxification Pathway by the Biocontrol Yeast Rhodotorula kratochvilovae LS11

Patulin (1) is a mycotoxin contaminant in fruit and vegetable products worldwide. Biocontrol agents, such as the yeast Rhodotorula kratochvilovae strain LS11, can reduce patulin (1) contamination in food. R. kratochvilovae LS11 converts patulin (1) into desoxypatulinic acid (DPA) (5), which is less cytotoxic than the mycotoxin (1) to in vitro human lymphocytes. In the present study, we report our investigations into the pathway of degradation of patulin (1) to DPA (5) by R. kratochvilovae. Isotopic labeling experiments revealed that 5 derives from patulin (1) through the hydrolysis of the γ-lactone ring and subsequent enzymatic modifications. The ability of patulin (1) and DPA (5) to cause genetic damage was also investigated by the cytokinesis-block micronucleus cytome assay on in vitro human lymphocytes. Patulin (1) was demonstrated to cause much higher chromosomal damage than DPA (5).

Patulin in Apples and Apple-Based Food Products: The Burdens and the Mitigation Strategies

Apples and apple-based products are among the most popular foods around the world for their delightful flavors and health benefits. However, the commonly found mold, Penicillium expansum invades wounded apples, causing the blue mold decay and ensuing the production of patulin, a mycotoxin that negatively affects human health. Patulin contamination in apple products has been a worldwide problem without a satisfactory solution yet. A comprehensive understanding of the factors and challenges associated with patulin accumulation in apples is essential for finding such a solution. This review will discuss the effects of the pathogenicity of Penicillium species, quality traits of apple cultivars, and environmental conditions on the severity of apple blue mold and patulin contamination. Moreover, beyond the complicated interactions of the three aforementioned factors, patulin control is also challenged by the lack of reliable detection methods in food matrices, as well as unclear degradation mechanisms and limited knowledge about the toxicities of the metabolites resulting from the degradations. As apple-based products are mainly produced with stored apples, pre- and post-harvest strategies are equally important for patulin mitigation. Before storage, disease-resistance breeding, orchard-management, and elicitor(s) application help control the patulin level by improving the storage qualities of apples and lowering fruit rot severity. From storage to processing, patulin mitigation strategies could benefit from the optimization of apple storage conditions, the elimination of rotten apples, and the safe and effective detoxification or biodegradation of patulin.

Paecilomyces Rot: A New Apple Disease

Paecilomyces niveus is an important food spoilage fungus that survives thermal processing in fruit products, where it produces the mycotoxin patulin. Spoilage of products has been attributed to soil contamination; however, little is known about the ecology of this organism. In this study, orchard soils and culled apple fruit were surveyed and the ability of P. niveus to infect apple was tested on two popular apple varieties. P. niveus was found in 34% of sampled orchard soils from across New York. Completing Koch's postulates, P. niveus was demonstrated to cause postharvest disease in Gala and Golden Delicious apple. Symptoms of this disease, named Paecilomyces rot, resemble several other apple diseases, including black rot, bitter rot, and bull's-eye rot. External symptoms of Paecilomyces rot include brown, circular, concentrically ringed lesions, with an internal rot that is firm and cone-shaped. Both Gala and Golden Delicious apple fruit inoculated with P. niveus developed lesions ≥43 mm in size at 22 days after inoculation. There is some evidence that the size of lesions and rate of infection differ between Gala and Golden Delicious, which may indicate differing resistance to P. niveus. This work shows that P. niveus is common in New York orchard soil and can cause a novel postharvest fruit disease. Whether infected fruit can serve as an overlooked source of inoculum in heat-processed apple products requires further study.

Apple Intrinsic Factors Modulating the Global Regulator, LaeA, the Patulin Gene Cluster and Patulin Accumulation During Fruit Colonization by Penicillium expansum

The mycotoxin patulin is produced in colonized tissue by Penicillium expansum during storage of apples and is significantly affected by environmental factors that contribute to its accumulation. Few reports have, however, examined the effect of natural intrinsic factors associated with the fruit on the production of patulin. Here, we find that with advancing maturity, Golden Delicious apples show increased concentrations of total soluble solids (TSS) from 14 to 17% associated with the increased expression of the global transcription factor involved in regulation of secondary metabolite biosynthesis in filamentous fungi, laeA expression and patulin accumulation. However, the apple cultivar Granny Smith, with similar TSS values but differing in pH levels and malic acid concentrations, showed reduced expression levels of laeA and the patulin biosynthesis gene cluster (pat genes) and patulin accumulation, suggesting a complexity of host factors contribution to patulin accumulation during P. expansum colonization. To start elucidating these apple intrinsic factors, we examined their in vitro impact on laeA and pat gene expression concomitant with patulin synthesis. Increasing sucrose concentrations from 15 to 175 mM repressed laeA and pat gene expression and patulin production. However, this affect was modified and often reversed and sometimes accentuated by changes in pH, or the addition of malic acid or the major apple phenolic compounds, chlorogenic acid and epicatechin. While the increase in malic acid from 0 to 1% increased laeA and pat gene expression, the decrease in pH from 3.5 to 2.5 reduced their expression. Also the increased laeA and pat genes expressions at increasing epicatechin concentrations from 0 to 1 mM, was reversed by increasing sucrose concentrations, all together suggesting the complexity of the interactions in vivo.